Ovarian cancer is stealthy, often presenting in advanced stages with little in the way of symptoms or warning. Sadly, the overall 5-year survival rate of women with advanced disease is less than 50%, earning ovarian cancer the inauspicious title of “the silent lady killer.” Treatment involves a combination of surgery and drugs, and the fate of the patient often relies on how much of the tumor the surgeon was able to remove. Now, van Dam and colleagues have pioneered an imaging technique in humans that allows surgeons to fluorescently label microscopic deposits of ovarian cancer and detect them in real time, on the operating table, using a multispectral fluorescence camera.

The concept is relatively is straightforward. Nearly all ovarian cancer cells overexpress membrane folate receptor-α (FR-α). In contrast, normal healthy cells rarely express this marker. van Dam et al. therefore conjugated folate—the natural ligand for FR-α—to a fluorescent dye called FITC. Folate-FITC was able to bind malignant ovarian cells so that they could be visualized during surgery. The authors applied this imaging technique to four patients with ovarian cancer and five control patients with benign ovarian tumors. Three of the four ovarian cancers expressed FR-α, and as expected, none of the benign tumors expressed this receptor. The number of tumor deposits identified with folate-FITC imaging was significantly higher than those identified by visual inspection alone. Fluorescence imaging successfully enabled surgeons to remove tumor deposits as small as 1 mm in size—a size that would have been missed by the naked eye. Although larger studies are needed to determine whether intraoperative fluorescence imaging will improve patient health, this proof-of-concept study illuminates a promising new direction for the surgical treatment of ovarian cancer.